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The impact of increasing Cd2+ exposure on the quality and quantity of siderophores produced by a plant growth promoting Pseudomonas fulva strain was tested to gain insight into the degree of change. P. fulva was cultured in the increasing concentrations of Cd2+ (0, 0.5, 1.0, 2.0 mM). The secreted siderophores were separated by HPLC and characterized by UHPLC‐QTOF/MS. In the presence of 2 mM Cd2+ synthesis of siderophores (hydroxamates, catecholates, phenolates) was mitigated compared to the treatments with lower concentrations of Cd2+ (0.5 and 1 mM). Increased synthesis of catecholates in 0.5 and 1 mM Cd2+ and of phenolates in 0.5–2 mM Cd2+ was revealed compared to the variant without Cd2+. Out of seven different hydroxamates, the secretion of ferrioxamine E was significantly decreased in the highest Cd2+ concentration. Two additional ferrioxamines, X2 and D2, were secreted independent of the presence or absence of Cd2+. Exposure to Cd2+ change the composition of siderophores secreted by P. fulva with selective promotion of catecholates and phenolates at the expense of hydroxamates. Successful adaptation in a Cd‐contaminated soil in the frame of practical applications to promote phytoremediation can be assumed. [ABSTRACT FROM AUTHOR]

Alnus glutinosa (black alder) is a mycorrhizal pioneer tree species with tolerance to high concentrations of salt in the soil and can therefore be considered to be an important tree for the regeneration of forests areas devastated by excessive salt. However, there is still a lack of information about the ectomycorrhizal fungi (EMF) associated with mature individuals of A. glutinosa growing in natural saline conditions. The main objective of this study was to test the effect of soil salinity and other physicochemical parameters on root tips colonized by EMF, as well as on the species richness and diversity of an EMF community associated with A. glutinosa growing in natural conditions. We identified a significant effect of soil salinity (expressed as electrical conductivity: ECe and EC1:5) on fungal taxa but not on the total level of EM fungal colonization on roots. Increasing soil salinity promoted dark-coloured EMF belonging to the order Thelephorales (Tomentella sp. and Thelephora sp.). These fungi are also commonly found in soils polluted with heavy-metal. The ability of these fungi to grow in contaminated soil may be due to the presence of melanine, a natural dark pigment and common wall component of the Thelephoraceae that is known to act as a protective interface between fungal metabolism and biotic and abiotic environmental stressors. Moreover, increased colonization of fungi belonging to the class of Leotiomycetes and Sordiomycetes, known as endophytic fungal species, was observed at the test sites, that contained a larger content of total phosphorus. This observation confirms the ability of commonly known endophytic fungi to form ectomycorrhizal structures on the roots of A. glutinosa under saline stress conditions. [ABSTRACT FROM AUTHOR]

Phytopathogenic fungi use a variety of strategies to infect hosts and have a diverse sensitivity to the natural defence mechanisms of the host plant, e.g. synthesis of phytoalexins. Many important pathogens of crops belong to the problematic genus Phoma, including species recently reallocated to Peyronellaea. The work presents: (1) molecular identification of five pathogenic strains of Peyronellaea (syn. Phoma) based on two loci, actin (ACT) and β-tubulin (TUB), and morphological observations; (2) differentiation of these strains based on their enzymatic activity; and (3) their effect on biosynthesis of phytoalexin in Hippeastrum scales. Phylogenetic analysis showed a close relationship between our strains and Peyronellaea curtisii (syn. Phoma narcissi) species. This was also supported by morpho-anatomical analysis although its results were less conclusive. Some phenotypic traits of the strains overlapped with characteristics of other Phoma s.l. species, allowing for misidentification based on morphology alone. Tested cellulolytic, pectolytic and amylolytic activities were strain specific. A high level of amylase activity was positively correlated with cellulase activity but negatively correlated with pectolytic activity. Moreover, some strains suppressed phytoalexin production in Hippeastrum scales and were resistant to various concentrations of phytoalexin added to the culture medium. Based on these results, we suggest that pathogenicity in P. curtisii strains is complex and that it may be associated with their interactive physiological potential for enzymatic attack and defence capabilities against phytoalexin. [ABSTRACT FROM AUTHOR]